FindCrypt.java

/*
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	                       Version 3, 29 June 2007
	
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	possible use to the public, the best way to achieve this is to make it
	free software which everyone can redistribute and change under these terms.
	
	  To do so, attach the following notices to the program.  It is safest
	to attach them to the start of each source file to most effectively
	state the exclusion of warranty; and each file should have at least
	the "copyright" line and a pointer to where the full notice is found.
	
	    <one line to give the program's name and a brief idea of what it does.>
	    Copyright (C) <year>  <name of author>
	
	    This program is free software: you can redistribute it and/or modify
	    it under the terms of the GNU General Public License as published by
	    the Free Software Foundation, either version 3 of the License, or
	    (at your option) any later version.
	
	    This program is distributed in the hope that it will be useful,
	    but WITHOUT ANY WARRANTY; without even the implied warranty of
	    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	    GNU General Public License for more details.
	
	    You should have received a copy of the GNU General Public License
	    along with this program.  If not, see <https://www.gnu.org/licenses/>.
	
	Also add information on how to contact you by electronic and paper mail.
	
	  If the program does terminal interaction, make it output a short
	notice like this when it starts in an interactive mode:
	
	    <program>  Copyright (C) <year>  <name of author>
	    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
	    This is free software, and you are welcome to redistribute it
	    under certain conditions; type `show c' for details.
	
	The hypothetical commands `show w' and `show c' should show the appropriate
	parts of the General Public License.  Of course, your program's commands
	might be different; for a GUI interface, you would use an "about box".
	
	  You should also get your employer (if you work as a programmer) or school,
	if any, to sign a "copyright disclaimer" for the program, if necessary.
	For more information on this, and how to apply and follow the GNU GPL, see
	<https://www.gnu.org/licenses/>.
	
	  The GNU General Public License does not permit incorporating your program
	into proprietary programs.  If your program is a subroutine library, you
	may consider it more useful to permit linking proprietary applications with
	the library.  If this is what you want to do, use the GNU Lesser General
	Public License instead of this License.  But first, please read
	<https://www.gnu.org/licenses/why-not-lgpl.html>.
 */

import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.Math;
import java.net.URL;
import java.net.URLConnection;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.security.Timestamp;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.zip.GZIPInputStream;

import docking.widgets.dialogs.MultiLineMessageDialog;
import ghidra.app.script.GhidraScript;
import ghidra.program.model.address.Address;
import ghidra.program.model.listing.Function;
import ghidra.util.Msg;

public class FindCrypt extends GhidraScript {
	private static final int 	CRYPT_COUNTER = 20;
	private static final double DETECT_THRESHOLD = 0.8;
	private static final int 	SKIP_SMALLER_SUB_CONSTANTS = 4;

	public static class InternalParams {
		// Disable automatic database update.
		public static final boolean __FORCE_NO_DBUPDATE = false;
		// Disable automatic script version check.
		public static final boolean __FORCE_NO_SCRIPTUPDATE = false;
		
		// Current script version, used for enforcing; modifications not recommended unless you know what you're doing.
		public static final String __SCRIPT_VERSION = "7";
	}

	public static class GuiHandler {
		
		public static void ShowMessage(String _title, String _message, String _details, int _icon) {
			MultiLineMessageDialog.showMessageDialog(null, _title, _message, _details, _icon);
		}
	}

	public static class UpdateManager {
		private String _BASE = "";
		private String _LOCAL = "";
		
		public String GetChangelog() {
			URL url;
			try {
				url = new URL(this._BASE + "/last_chlog.txt");
				URLConnection urlConnection = url.openConnection();
				InputStream in = new BufferedInputStream(urlConnection.getInputStream());

				var _lastchLog = new String(in.readAllBytes(), "UTF-8");
				
				return _lastchLog;
			} catch (Exception e) { 
				return "Error recovering last changelog:\n" + e.getMessage();
			}
		}
		
		public boolean CheckScriptVersion() {
			URL url;
			try {
				url = new URL(this._BASE + "/script_update.txt");
				URLConnection urlConnection = url.openConnection();
				InputStream in = new BufferedInputStream(urlConnection.getInputStream());

				var _last = Integer.parseInt(new String(in.readAllBytes(), "UTF-8"));
				var _local = Integer.parseInt(InternalParams.__SCRIPT_VERSION);
				
				if (_last > _local) {
					MultiLineMessageDialog.showMessageDialog(null, "FindCrypt Ghidra",
							"A new version of FindCrypt-Ghidra is available:", this.GetChangelog() + "\n\n\thttps://github.com/d3v1l401/FindCrypt-Ghidra", 1);
				}
				
				return true;
			} catch (Exception e) {
				// Don't bother, internet may not be available.
			}
			return false;
		}
		
		public boolean CheckDatabaseVersion() {
			URL url;
			try {
				url = new URL(this._BASE + "/last_update.txt");
				URLConnection urlConnection = url.openConnection();
				InputStream in = new BufferedInputStream(urlConnection.getInputStream());

				var _last = Integer.parseInt(new String(in.readAllBytes(), "UTF-8"));
				var _local = Integer.parseInt(new String(new FileInputStream(this._LOCAL + "last_update.txt").readAllBytes(), "UTF-8"));
				
				if (_last > _local) {
					System.out.println("A new version of the database is being downloaded (" + _local + " -> " + _last + ").");
					
					url = new URL(this._BASE + "/database.d3v");
					ReadableByteChannel readableByteChannel = Channels.newChannel(url.openStream());

					new File(this._LOCAL + "database.d3v").delete();
					FileOutputStream fileOutputStream = new FileOutputStream(this._LOCAL + "database.d3v");
					FileChannel fileChannel = fileOutputStream.getChannel();
					fileOutputStream.getChannel().transferFrom(readableByteChannel, 0, Long.MAX_VALUE);
					fileOutputStream.close();
					
					new File(this._LOCAL + "last_update.txt").delete();
					var _handle = new FileWriter(this._LOCAL + "last_update.txt");
					_handle.write(String.valueOf(_last));
					_handle.close();
				}
				
				return true;
			} catch (Exception e) {
				// Don't bother, internet may not be available.
			}
			return false;
		}
		
		public UpdateManager(String _baseUrl, String _basePath) {
			this._BASE = _baseUrl;
			this._LOCAL = _basePath;
		}
		
		
	}

	public static class DatabaseManager {
		// Structure of database file, for reference.
		/*******************************************************************
		 | MAGIC (4)    | Total Entries (2)           	                   |
		 | NameSize (4) | Name (x) | isCompressed(1) | ESize(4) | BSize(4) |
		 | Buffer (x)   | ...                                              |
		 ******************************************************************/
		
		// Structure of the database entry.
		public class EntryInfo {
			private byte[] _buffer;
			private String _name;
			private int _elementSize;
			
			public EntryInfo(byte[] _buff, int _elementSize, String _name) {
				this._buffer = _buff;
				this._elementSize = _elementSize;
				this._name = _name;
			}
		}
		
		private boolean   		 	_loaded = false;
		private static final int 	_EXPECTED_MAGIC = 0xD3010401;
		private short     		 	_totalEntries 	 = 0;
		
		private ArrayList<EntryInfo> _consts = new ArrayList<>();
		
		public int DbSize() {
			return this._totalEntries;
		}
		
		public DatabaseManager(String _path) {
			
			if (!this._loaded) {
				
				try {
					DataInputStream _stream = new DataInputStream(new FileInputStream(_path));
					var _curMagic = _stream.readInt();
					
					if (_curMagic != _EXPECTED_MAGIC)
						throw new Exception("Specified database file has a different magic from the expected one.");
					
					this._totalEntries = _stream.readShort();
					if (this._totalEntries == 0) {
						GuiHandler.ShowMessage("FindCrypt - Warning", "Something unusual happened while loading the database.",
								"The database contains no entries, while this is not error, the script will not scan anything", 2);
						return; // No need to proceed at all.
					}
					
					for (var i = 0; i < this._totalEntries; i++) {
						var _nameSize = _stream.readInt();
						if (_nameSize == 0)
							throw new Exception("An entry has 0 length name.");
						var _name = new byte[_nameSize];
						_stream.read(_name);
						
						var _isCompressed = _stream.readByte();
						var _elementSize = _stream.readInt();
						var _buffSize = _stream.readInt();
						if (_buffSize == 0) 
							throw new Exception("An entry has no buffer (" + _name + ")");
						var _buff = new byte[_buffSize];
						_stream.read(_buff);
						
						if (_isCompressed == 0x01) {
							// https://stackoverflow.com/questions/12531579/uncompress-a-gzip-string-in-java
							ByteArrayInputStream bytein = new ByteArrayInputStream(_buff);
							GZIPInputStream gzin = new GZIPInputStream(bytein);
							ByteArrayOutputStream byteout = new ByteArrayOutputStream();

							int res = 0;
							byte buf[] = new byte[1024];
							while (res >= 0) {
							    res = gzin.read(buf, 0, buf.length);
							    if (res > 0) {
							        byteout.write(buf, 0, res);
							    }
							}
							byte uncompressed[] = byteout.toByteArray();
							
							this._consts.add(new EntryInfo(uncompressed, _elementSize, new String(_name, "UTF-8")));
						} else 
							this._consts.add(new EntryInfo(_buff, _elementSize, new String(_name, "UTF-8")));
					}
					
					_stream.close();
					this._loaded = true;
					
				} catch (Exception e) {
					GuiHandler.ShowMessage("FindCrypt - Error" , "An error happened while loading the database.", e.getMessage(), 0);
				}
				
			}
			
		}
	}

	public static class WorksetManager {
		private static final String __FCUPD_BASEURL = "https://raw.githubusercontent.com/d3v1l401/FindCrypt-Ghidra/master/findcrypt_ghidra";
		
		private static final String __FCDATA_DIR = System.getProperty("user.home") + File.separator + "findcrypt_ghidra" + File.separator;
		
		private static DatabaseManager _dbHandler;
		private static UpdateManager   _updHandler;
		
		public static boolean Initialize() {
			_dbHandler = new DatabaseManager(__FCDATA_DIR + "database.d3v");
			_updHandler = new UpdateManager(__FCUPD_BASEURL, __FCDATA_DIR);
			
			if (_dbHandler != null && _updHandler != null) {
				_updHandler.CheckDatabaseVersion();
				_updHandler.CheckScriptVersion();
				return true;
			}
			
			return false;
		}
		
		public static int GetDatabaseSize() {
			return _dbHandler.DbSize();
		}
		
		public static ArrayList<DatabaseManager.EntryInfo> GetDB() {
			return _dbHandler._consts;
		}
	}

	public class FoundCryptoEntry {
		private String _name;
		private Address _address;
		private Function _function;
			
		public FoundCryptoEntry(String _name, Address _address, Function _function) {
			this._name = _name;
			this._address = _address;
			this._function = _function;
		}

		public String toString() {
			if (_function != null) {
				return String.format("%s (%s) -> %s\n", _function.getName(), _name, _address.toString());
			} else {
				return String.format("%s -> %s\n", _name, _address.toString());
			}
		}
	}

	public class FoundCryptoEntries extends ArrayList<FoundCryptoEntry> {
	}
	
	@Override
	protected void run() throws Exception {
			
		println("FindCrypt - Ghidra Edition by d3vil401 (https://d3vsite.org)\n" +
					"Special thanks to Pawlos for fragmented constant scans\n" + 
					"Original idea by Ilfak Guilfanov (http://hexblog.com)" +
					"\n");
		
		Boolean headless = isRunningHeadless();
			
		if (currentProgram == null) {
			Msg.info(this, "No program loaded, aborting.");
			return;
		}
		
		WorksetManager.Initialize();

		println("Loaded " + WorksetManager.GetDatabaseSize() + " signatures.");
		
		var _formatted = "";

		var foundEntries = new FoundCryptoEntries();
		
		for (var alg: WorksetManager.GetDB()) {
			monitor.checkCanceled();
			
			var _found = currentProgram.getMemory().findBytes(currentProgram.getMinAddress(), alg._buffer, null, true, monitor);
			if (_found != null) {
				var function = currentProgram.getFunctionManager().getFunctionContaining(_found);
				foundEntries.add(new FoundCryptoEntry(alg._name, _found, function));
			} else {
				if (alg._elementSize < SKIP_SMALLER_SUB_CONSTANTS) {
					continue; //skip too small constants - too many false positvies 
				}
				var size = alg._buffer.length;
				byte[] part = new byte[alg._elementSize];
				var realHowManySubItems = size/alg._elementSize;				
				var howManySubItemsToCheck = Math.min(realHowManySubItems, CRYPT_COUNTER);				
				var howManyFound = 0;
				ArrayList<Address> _addresses = new ArrayList<>();
				for(var i = 0; i < howManySubItemsToCheck; i++) {
					var offset = i * alg._elementSize;
					System.arraycopy(alg._buffer, offset, part, 0, alg._elementSize);		
					var _foundPart = currentProgram.getMemory().findBytes(currentProgram.getMinAddress(), part, null, true, monitor);
					if (_foundPart != null) {
						_addresses.add(_foundPart);
						howManyFound++;
					}
				}				
				if (howManyFound / realHowManySubItems >= DETECT_THRESHOLD) {
					var firstAddress = _addresses.get(0);
					var function = currentProgram.getFunctionManager().getFunctionContaining(firstAddress);
					foundEntries.add(new FoundCryptoEntry(alg._name, firstAddress, function));
				}
			}
		}

		var _ctr = 0;
		for (var entry: foundEntries) {
			_formatted += entry.toString()+"\r\n";
			_ctr++;
		}
		
		// Only show results if something has been found.
		if (_ctr >= 1) {		
			if (headless) {
				println("A total of " + _ctr + " signatures have been found.\r\n"+_formatted);				
			} else {
				GuiHandler.ShowMessage("FindCrypt Ghidra", "A total of " + _ctr + " signatures have been found.", _formatted, 1);
			}
		}
		
		_formatted = "";
	}

}